Field of Invention
The present invention belongs to the field of agricultural non-point source pollution control, and particularly relates to an integrated device and method for eliminating initial runoff pollution.
Description of Related Arts
In recent years, a large amount of researches are performed on the loss characteristics of the farmland runoff contaminants in China and other countries. The research showed that the peak values of the concentrations of nitrogen and phosphorus in the runoff appear in half an hour even the shorter time after the runoff is induced. Afterwards, the concentration of nitrogen and phosphorus in the runoff is mainly related to that of the rainwater itself. It is important for mitigating the agricultural non-point source pollution to control the discharge of the initial runoff during the period with a higher concentration. As to the ecological environment, the rice field can be defined as a shallow water wetland which greatly influences the transformation processes of nitrogen and phosphorus in the surface runoff with the function of regulating discharge of excess water and circulation of nutrient in the agricultural production base. Thus, taking advantage of making full use of the initial runoff generated by high niche from the rice field as an effective method can maximize the reduction of the pollutant output.
A Chinese patent with an application number of CN201410625297.0 discloses an ecological ditch system with interception function for controlling rice-field non-point source pollution, comprising two parts: the ecological ditch and paddywetland; wherein the wall of the ecological ditch is provided with green plant, the bottom is provided with emerging plant, and rice is planted in the paddy wetland whose resource of the irrigation water and the fertilizer is water flowing from the upstream and through the rice field and the ecological ditch. The system plays a certain role in contaminants elimination, but the utilization efficiency is limited by the capacity of the ditch and the rice field, which results in the system cannot maximize the reduction of contaminants during the storm period.
A Chinese patent application with an application number of CN201510245277.5 discloses a method for controlling the rice field non-point source pollution and an artificial paddy wetland system, wherein the rice field wetland system improves the utilization rate of nitrogen and phosphorus. The system structure takes the rice field as an upstream, and a paddy wetland is constructed in the drain downstream of the rice field beside a river. This patent makes good use of the blocking, absorbing and utilizing effects to the contaminants of the water body by the rice field itself, so as to reduce the contaminants in the discharged water, but there is an efficiency problem similar to the previous patent.
A Chinese patent application with an application number of CN201510183146.9 discloses a collection and irrigation system for initial runoff from an agricultural land, comprising: drainage ditches, diversion canals, drains ditch weirs, initial runoff sensors, electric catchment valves, catchments, lift pumps, agricultural irrigation pipelines and farmland irrigation nozzles; wherein a square drainage channel used in non-flush period is built on an upper position of drain weir, the electric catchment valves controlled by the initial runoff sensor is set on the diversion canals, so as to collect the initial runoff for daily agricultural irrigation. The system accumulates the initial runoff through the sump for subsequent irrigation, but there is also a problem that the storage capacity is limited during the storm period.
A Chinese patent application with an application number of CN201510890262.4 discloses a system for rice field non-point source pollution control, and recovery and utilization of nitrogen and phosphorus. When the rice field is drained, the water flows through each unit, adsorbs nitrogen and phosphorus through their adsorbates, and further reduces the concentration of nitrogen and phosphorus in water by the artificial wetland absorption for to achieve the purpose of reducing the risk of water eutrophication; when rice fields are irrigated, the water flows through the adsorption unit into the irrigation ditch, the absorbing substances release the nitrogen and phosphorus substances adsorbed to the irrigation water by desorption for reutilization in the rice field. Compared with the former systems mentioned above, this patent is capable of improving the eliminating efficiency of the contaminants by cycling the tailwater. However, the complex facilities and failure analysis to the pollutant concentration in different stages of the rice field ecosystem requests efficiency to be further improved.